The present invention relates to the recovery of the metal content of oxide or sulfide containing ores such as pyrite ores. As is well known, pyrite, pyrrhotite and related type ores contain many valuable metals, including arsenic, nickel, cobalt, copper and gold in addition to iron. Although these metals are quite valuable, it is difficult to separate and recover such metals efficiently and effectively for several reasons. First, many such ores, especially the pyrites, contain large sulfur content, which requires carefully controlled processing for removal and disposition. This is particularly significant at the present time due to the widespread interest in avoiding or minimizing atmospheric pollution.
Also, with many ores, the metals are intimately associated with silica, which makes separation and recovery difficult and expensive, particularly with metals such as iron, nickel and cobalt which readily combine with silica to form the respective silicates. Moreover, in either sintering or smelting processes, which have customarily been used to separate the metal contents, high temperatures are normally required with ores having a significant silica content, which poses highly significant problems in the selection of suitable equipment capable of maintaining high temperatures for extended periods of time.
In processes previously used, it has been common practice to utilize carbonaceous reducing agents to achieve separation of metals such as iron, nickel or cobalt. The carbonaceous reducing agents are normally intimately admixed with the ore, after which the admixture is roasted at temperatures substantially higher than 1500.degree. Centigrade to reduce the metal oxides and sulfides to the metal state. The use of carbonaceous reducing agents suffers from the disadvantage that significant quantities of the reducing agents are lost during ignition. It is also necessary to control carefully the furnace atmosphere during roasting to achieve metallization. By the same token, an elaborate heating system is generally required to produce and maintain the high temperature which is necessary during roasting.